Continuous tube rolling mill



June 12, 1945. BANNlSTER 2,378,278

CONTINUOUS TUBE ROLLING MILL Filed Sept. 29, 1942 2 Sheets-Sheet l llllllyll" 7 l4- lNVjENTORI June 12, 1945. Mm 2,37s,27s

CONTINUOUS TUBE ROLLING MILL Filed Sept. 29, 1942 2 Sheets-Sheet 2 F-IFE'QE'.

\.3 AI. 9 'i l] 22002250 5574/1 7 flaw/W5 TEE, v

Patented June 12,1945

UNITED STATES PATENT OFFICE CONTINUOUS TUBE ROLLING MILL Bryant Bannister, Mount Lebanon, Pa., assignor to National Tube Company, a corporation of New Jersey Application September 29, r942, Serial No. 460,151

8 Claims.

comprises a series of roll stands arranged in tandem with the rolls of each stand being grooved and with each ,stand being individually driven. The rolls of the stands compress and displace the metal of a pierced billet on a cylindrical mandrel arranged within the billet as the 'billet which is adapted to be formed into tubing passes continuously through the consecutivelyv arranged rollstands of the mill. This type of mill corresponds to the conventional multiple stand mills for roll-' ing flat sheets 'or plates from heated slabs of metal. In both types of mills, under ideal-conditions, the speed of each roll stand should be such that it tends to take metal from the preceding stand at substantially the same rate that the metal is delivered from such stand. It will be seen that if the speed of the rolls of'the respective stands is too great to meet this condition that portion of the metal between the stands while being rolled tends to be stretched and if the speed of the rolls is too low the metal-is subjected to compression, or looping occurs between the stands. 7

In a sheet orjpla'te mill it is comparatively simplc to adjust properly the roll speeds for there is nothing between the stands except the sheet or workpiece and various means have been suggested and used for equalizing the speed of the rolls in such mills. However, in a tube rolling mill, in addition to the billet or workpiece between each of the stands, there is arranged Within the'billet'a rigid mandrel for supporting the metal during the working thereof by the rolls of the stands, a factwell known to those skilled in the art of tube rolling. In atube mill it will be seen that the mandrel'will travel at only one speed through the roll stands at any one time, which speed is ticular stand not fast enough or too fast, the speed'of the roll standto which it is being delivered may be regulated so that stresses are eliminated from that portion of the billet or workpiece disposed between the stands. It is to such means and method of determining whether the workpiece between the stands is under stress, 1. e. compression or tension, that the present invention relates.

Accordingly, it is the general object of the present invention to provide in a continuous tube rolling mill an improved means for and method of determinin the stress condition of that portion of a tube or workpiece disposed between the succeeding stands of the mill.

It is another object of the invention to provide an improved means forgand method of indicating v in a continuous tube rolling mill whether that portion oftheworkpiece between the respective stands of the mill is under tension or'compression.

It is a .further object of this invention to provide .an improved method of operating a continuous tube rolling mill which comprises deter mining whether that portion of the billet-or workpiece between the succeeding stands of the mill faster than the peripheral speed of the rolls in F the first stands of the mill and slower in the later stands. Also, the speed of the mandrel changes from the time it enters the mill until the time it leaves and it is desirable that the metalof the billet or tubing around the mandrel between adjacent roll stands be neither in tension nor compression. It will be understood that if such ideal conditions are maintained, slippage, wear on the rolls and loss ofpower are reduced to a minimum.

It will be seen then that if it can be ascertained whether the billet or workpiece passing through the stands or mill is being delivered from any paris under either compression or tension, and then regulating the speeds of the rolls of the respective stands so that the workpiece is not subject to either tension or compression.

Various other objects and advantages of this invention will become more apparent during the course of the, following specification and will be particularly pointed out in the appended claims. In the accompanying drawings there is shown for the purpose of illustration an embod.ment which my invention may assume in practice.

In-the drawings: a

Figure 1 is a plan view, partly in section, of any two roll stands of a continuous tube rolling mill showing the positions the workpiece and mandrel assume while passing the ethrou-gh and with which the improved indicating means ofmy in vention is shown incorporated;

Figure 1A is a sectionalview taken on line IA IA of Figure 1;

' Figure 1B is a sectional view taken on line 13-- lBofFigurel; n

Figure 2 is arsectional view taken on line II-II Figure 3 is a view taken at right angles to the .View shown in Figure 1 showing only one roll stand and the; position of my improved indicating means relative to the rolls thereof, with the workpiece shown therein being under normal stress;

f Figure. 4 is a view similar to Figure 3 showing but showing a modification having a speed control for the motor of the successive roll stand.

Referring more particularly to the drawings,

there are shown in Figure 1 for the purpose of illustration two roll stands 2 and 3, each having opposed grooved rolls 4. It will be understood that these two roll stands as shown may be any two stands of a conventional continuous tube rolling mill in which the roll stands are arranged in tandem. There is shown disposed in and passing through the roll stands 2 and I a workpiece or billet B having a cylindrical mandrel M arranged therewithin, both of which pass between the stands in a well-known manner. In order to determine the stress conditions of the workpiece between the stands such as the two shown in the present instance, it will be understood that it isnecessary to derive such information from the workpiece or billet itself while the same passes between the stands of the mill. It will be noted that the workpiece or billet B has a decided oval cross section while in and immediately after leaving stand 2 as shown in Figure 1A of the drawings and that it has a similar oval cross section while in and immediately after leaving stand 3 but the long and short axes of the oval cross section of the workpiece or billet are displaced 90 in stand 3 from their position in stand 2 as shown in Figure 1B of the drawings. force acting upon the workpiece or billet between stands 2 and I there is no influence to alter the shape or position of the oval cross section of the billet immediately after leaving stand I until it reaches a point near stand I where the long and short axes necessarily reverse their positions due .to the fact that the axesvof the rolls 4 in stand 3 are-positioned substantially perpendicular to the axes of the rolls 4 in stand 2. Thus, it will be seen that from the axiallength and cross section of this transition zone of the billet bctweenthe stands, stands 2 and 8 in the present instance.

the stresses in the workpiece or billet can be;

ascertained. For example, if the pivotal speed of the rolls 4 in stand I is greater than that of the entering workpiece or billet, tension will result in that portion of the workpiece between stands I and 3 and the length of the transition zone will be increased with the vertical shorter while the "horizontal axis become greater. It will be understood that the basis of this phenomenon is that the shortest distance be- Y tween two points is a straight line. Such a result applies in the present instance for the reason that the rolls in stand 8 grip-the workpiece at the top and bottom thereof as shown, compressing it against the mandrel within the workpiece, thereby tending. to pull more metal into the pass tween the rolls of the'stand than is being lull ed y stand 2 thereby tending to straighten .o t the hump or projecting portion or the workpi e occurring immediately ahead oi stand I. The flare in the'grooved rolls'of stand 8 permits the hori- Since there is no external becoming I. Such action will shorten the transition zone and cause the horizontal axis of the oval section also to remain constant until it reaches a point closer to stand 3.

According tov the present inventionit is pro posed to utilize the above-outlined phenomenon to ascertain whether that portion of the workpiece or billet 3 between any two stands is under stress, namely tension or compression, and then to regulate the speed of. the rolls of the respective stands so as to eliminate the stress condition so that the workpiece or billet is subjected to neither compression nor tension. In order to carry out the teachings of the present invention there is arranged at a point: immediately in front of the rolls 4 of the advanced stand, or stand 3 as shown in the present instance, means for contacting the workpiece or billet as it passes between the stands stood that any suitable contact means may be .used for indicating the stress condition of the workpiece between the stands. In the present instance there is shown a means which is most suitable for ascertaining this stress condition. As

shown in Figures 1 and 2 of the drawings there is .positioned adjacent the advanced stand, or stand 3 as shown, a supporting means or bracket 5 having a threaded aperture 8 arranged therethrough. 'ghere is arranged in the threaded aperture of the bracket I an exteriorly threaded collar or sleeve member I. There is slidably arranged through the collar 1, a rod 8 for reciprocable movement.

Onthe outer end of the rod 8 there is mounted a forked member 9 between the legs of which there is rotatably mounted a roller. |0 on pin i2. Around the slidable rod 8 and between the forked member 0 and the sleeve 1 there is disposed preferably a coil spring. The-roller i0 is disposed preferably at a point in the crotch between the rolls 4 of the advanced stand, or stand I as shown in Figure 1 of the drawings. It will be understood that the roller I0 is adapted to contact the' outer side wall of the workpiece or billet at all 1 ing means i4 is pivotally connected to the outer end of the shaft or rod 0 at II. There is securely carried by the shaft or rod 0 at a point beyond the sleeve 1, a collar member I! which is adapted to limit'the inner movement of the rod or shaft I.

. Adiacent the outer end of the pointer or indicatmeans l4 there is arranged preferably a seamental dia-l member ll having calibrations l8 arranged thereon with which the pointer or indicstor i4 is adaptedto cooperate so as to indicate the stress conditions of the workpiece or billet.

sontal axis of the workpiece to increase as the vertical axis decreases since the perimeter of the oval cross section remains unchanged. Converse As shown in Figure 6, the contactin device may be connected to a-variable speed motor-which drives the rolls of the successive stand, adjacent the contactor. In the arrangement shown, the arm l4c-is.in contact with a resistance 20 and is connected in series therewith to a source or power and field II of the roll motor. Armature 22 of the roll motor is likewise connected to a suitable rolls in stand 8 is less than the rate of speed source of power. Thus it is seen that as the roller moves inwardly or outwardly, more orless r'esistance will be placed in the-circuit to slow or speed untilthe workpiece reaches apoint closer'to stand 7 up the roll motor. Thus the speed of the motor l'wi1l move outwardly as the horizontal axis of the workpiece increases and inwardly as the horizontal axis decreases and as the workpiece is subjected to compression stresses. Between these two extremes it 'will be understood that the workpiece is under practically no stress. Thus it will be seen that when that, portion of the workpiece or billet between stands 2 and 3 is under tension the roller l0 together with the shaft or rod 3 upon which it is mounted will move outwardly and the pointer or indicating means will move about its pivotal connection at 15 and indicate on the calibrations I9 of the dial l8 that the I workpiece or billet is under tension as shown in Figure 5 of the drawings. If that portion of the workpiece between stands 2 and .3 is under compression the roller l0 together with the shaft or rod 8 will move inwardly thereby moving the indicating means or pointer l4 about its pivotal connection so as to indicate on the dial l8 that dicate a neutral or'no'rmal position as shown in Figure 3 of the drawings. After it has been determined whether or not the workpiece between the roll stands is under compression or tension,

the speed of the respective rolls of the stands is increased or decreased so as to satisfy the condition until the indicating means or pointer M will 'assume a normal condition as shown in Figure. 3

of the drawings which, of course, is the ideal operating condition of the mill. It will be understood that a device or mechanism similar to that shown inthe drawings is mounted immediately ahead of eachroll stand of the mill exceptin the first stand. It it obvious that the contacting member or roller Ill can be actuated by the metal of the workpiece or billet in the plane of either the long or short axis of the transition zone, whichever is desired. In the arrangement shown in Figured the contacting devices are interconnected with the roll motors so that the roll speeds are automatically regulated.

As a result of my invention it will be seen that there is provided not 'only a simple and inexpensive means for determining whether the workpiece or billet between the stands is under compression or tension but at the same time means which is efficient and effective in its operation and use. .It will be seen that by, the practice 'of the present inventionthe speed of the rolls of the respective stands can beaccurately maintained so that the metal is supplied to. the re- *s'pective stands at the correct sp ed thereby'P viding a finished tubing which has proper dimensions and improved qualities.

' While-I have shown and described one specific embodiment of my invention, it will be under-- will be automatically varied to reduce tension or Q compression in the workpiece.

scope of my invention, as defined in the appended claims.

.Iclaim:

1. In a continuous tube rolling mill having a plurality of spaced apart roll stands, a roller arranged between at least some of the roll stands which contacts the outer side wall of the tubing as it passes continuously therethrough, said roller having the axis thereof arranged substantially perpendicular to theaxis of the tubing, movable means upon which said roller is rotatably mounted, said movable means adapted to move diametrically of the tubing and being responsive to the lateral movement of the roller together with the side walls of the tubing, and means responsive to the movement of said movable means together with said roller for indicating whether the portion of the tubing between the respective stands is under tension or compression. 7

2. In a continuous tube rolling mill having a pluralityof spaced apart roll stands, a roller arranged between at least some of the roll stands which contactsthe outer side wall of the tubing as it passes continuously therethrough, said roller having the axis thereof arranged substantially perpendicular to the axis of the tubing, movable means upon which said roller is rotatably mounted, said means adapted to move diametrically of the tubing and being responsive to th lateral movement of the roller together-with the side walls of the tubing, a pointer which is mounted for pivotal movement, said movable means connected to said pointer which it is adapted to actuate, and means with which said pointer cooperates to indicate whether the portion of the tubing between the respective stands is under tension or compression.

3. In combination with a continuous tube rolling mill having a plurality of spaced apart roll stands and a mandrel which is adapted to be disposed within the tubing, meansarranged between at least two of the roll stands adjacent the transition zone'for contacting theouter side walls of the tubing as the same together with the mandrel passes continuously therealong which is responsive to the variations in diameter of the tubing at the transition zone between the respective roll stands so as to determine. whether that portion of the tubing between the roll stands is under tension or compression, said transition zone being that point between the roll stands atWhich the axis of the oval cross-section of the tubing changes from one plane to another.

4. In a'continuous tube rolling mill having a plurality of spaced apart roll stands wherein a tubular workpiece is rolled on a mandrel bar and an oval shape imparted thereto with the axis f ovality changed by successive stands, means responsive to variations in said ovality arranged adjacent the inlet side of a successive stand for determining the amount ofreduction of such ovality by such stand ata spaced point in advance thereof to thereby determine whether the worka the speed of the rolls thereof to control the tentubular workpiece is rolled on a' mandrel bar and an oval shape imparted thereto with the axis of ovality changed by successive stands, means responsive to variations in said ovality' arranged adjacent the inlet side of a successiv stand for determining the amount or reduction oi. such ovality' by such stand at a spaced'point in advance thereof, and means connected thereto to indicate whether the workpiece is under tension or compression asit enters such stand. 6. In a continuous tube rolling mill having a plurality oi spaced apart roll stands wherein a tubular workpiece is rolled on a mandrel-bar and an oval shape imparted thereto with the axis of ovality changed by successive stands, means engaging an oval portion of the tube wall. adjacent the inlet side of a successive stand for determin-' ing the amount of. reduction of such ovality by suchstand at a spaced point in advance thereof to thereby determine whether the workpiece is under tension or compression as it enters such stand. and means connected thereto to vary the speed or the-rolls thereof to control the tension or compression in the workpiece as it enters such stand.

'7. In a continuous tube rolling mill having a plurality oispa'ced apart roll stands wherein a tubular workpiece is rolled on a mandrel bar censure and an oval shape imparted thereto with the axis of ovality changed by successive stands. means engaging an oval portion of the tube wall adiacent the inlet side of a successive stand for determining the amount oi reduction of such ovality by such stand at a spaced point in advance thereof. and means connected thereto to indicate whether the workpiece is under tension or compression as it enters such stand.

8. In the art 0! continuously rolling tubing in a continuous tube rolling mill wherein a tubular workpiece is rolled on a mandrel which moves therewith in a succession of roll stands wherein an oval shape is imparted thereto with the axis oi. ovality or the tube changed by successive stands, the steps of determining the amount of such ovality at a spaced point in advance oi a successive stand to determine whether the workpiece is under tension or compression as it enters such stand and .varyinc the speed of the rolls of such stand so as to control the tension or compression therein as it enters such roll stand.

- BRYANT 

